In the prior art motor assemblies including a prime mover, a gear reduction unit capable through successive stepdown of supplying the desired power take-off through an output shaft, and a pair of electrical leads for applying power to the prime mover are known. Representative of such prior art teachings is U.S. Pat. No. 3,268,751 which issued in the names of Alfred M. Nebiolo and Robert S. Lundin, one of the co-inventors' herein. While the above-noted motor assembly adequately served the purposes for which it was designed and was accepted commercially it suffers in that it has a major disadvantage, namely that each of the various parts including the prime mover, the gear reduction unit, the output shaft and the electrical leads are permanently fastened together so that interchangeability of parts is difficult if not impossible. Therefore, the motor assembly is limited in application by the rating of the prime mover, the stepdown capability of the gear reduction unit, the style of the shank of the output shaft which couples to a member to be driven, and the type of electrical lead which limits placement of the motor assembly and/or the type of connector for attachment with the lead terminals.
As should be apparent with the above assembly there is a need to stock many different units to meet differing requirements for production, R & D or other uses. This need has a decided impact in inventory levels to be maintained and the costs attendant therewith. The impact is felt both by the supplier and the user of the motor assembly.
The prior art teaching of U.S. Pat. No. 3,676,725 to Wiser et al. is representative of those teachings which directed themselves to the question of interchangeability of parts of structures as outlined above. The Wiser et al. patent relates to the interchangeability of one reduction unit for another and the capability of mounting each of several gear reduction units to the prime mover.
While the Wiser et al. patent directs itself to the question of interchangeability of parts it falls short of the objective attained by the present invention. To this end, the Wiser et al. patent and other patents of like teaching provide no capability of selectively locking in an output shaft in cooperative driven relation with the gears of a gear reduction unit.
Thus, Wiser et al. is limited in use by the style configuration of the output shaft coupling means of the particular gear reduction unit to be used with the prime mover.